Filter and cleaning method

ABSTRACT

The invention relates to a filter (10) for a suction device, in particular a vacuum cleaner, a wet vacuum cleaner or the like, to a suction device, and to a cleaning method, the filter comprising a filter housing (11) within which a suction air duct (12) for conveying a suction air flow is formed, the filter housing having a centrifugal separator (13) for separating particles from the suction air flow and a container (14) for collecting the separated particles. The filter has a metering device (15) disposed upstream of the centrifugal separator in a flow direction of the suction air flow, the metering device being configured to spray liquid into the suction air flow.

The invention relates to a filter for a suction device, in particular a vacuum cleaner, a wet vacuum cleaner or the like, to a suction device, and to a cleaning method, the filter comprising a filter housing within which a suction air duct for conveying a suction air flow is formed, the filter housing having a centrifugal separator for separating particles from the suction air flow and a container for collecting the separated particles.

Filters of this kind are sufficiently known and are commonly used for suction devices. Suction devices referred to as vacuum cleaners serve as mobile devices for cleaning surfaces, in particular floor coverings. A turbine for generating a suction air flow and a filter are disposed within a housing of the vacuum cleaner. In particular, a distinction is made between vacuum cleaners with filter bags, bagless vacuum cleaners, vacuum cleaners with a liquid filter or a water filter, and spray extraction vacuum cleaners.

In the case of liquid filters, a suction air flow is led through a liquid container, dust particles being wetted with liquid or water and trapped. The disadvantage here is that the suction device cannot be used unless the liquid filter is filled with a sufficient amount of liquid. A wettable surface of the liquid which an air flow is led past continuously decreases in the process, dust particles coming into contact with the liquid less and less. Also, a suction device of this kind cannot be tilted and moved into a position which impedes the filter effect of the liquid filter or causes it to leak. Furthermore, bagless filters are known which typically have one or more centrifugal separators. In a centrifugal separator, a rotating eddy is produced in the suction air flow, particles, such as dust, fibers, small objects, house dust, etc. being conveyed to a wall of the centrifugal separator because of their mass and dropping down into a collecting container or the like. However, the disadvantage here is that the cleaned suction air flow may still contain dust, in particular since particles located in the collecting container may be raised. Moreover, undesired smells may be released back into an environment after passage through said filter. Particulate matter can easily be released when emptying the collecting container, for example, when beating the collecting container. Also, particulate matter may remain in the collecting container and reenter the suction air flow.

Hence, the object of the present invention is to propose a filter, a suction device having such a filter, and a cleaning method which overcome the disadvantages known from the state of the art.

This object is attained by a filter having the features of claim 1, a suction device having the features of claim 20, and a cleaning method having the features of claim 21.

The filter according to the invention for a suction device, in particular a vacuum cleaner, a wet vacuum cleaner or the like, comprises a filter housing within which a suction air duct for conveying a suction air flow is formed, the filter housing having a centrifugal separator for separating particles from the suction air flow and a container for collecting the separated particles, wherein the filter has a metering device which is disposed upstream of the centrifugal separator in a flow direction of the suction air flow, the metering device being configured to spray liquid into the suction air flow.

Consequently, the filter is essentially composed of the centrifugal separator and the container for collecting the separated particles. Thus, it is possible for the filter to be used as a bagless filter by solely using the centrifugal separator which causes the separated particles to drop into the container. The particles can be common household dirt, such as dust, fibers, small objects, house dust, etc. The fact that the filter has a metering device makes it possible for the filter to also be used as a liquid filter. If the container is filled with liquid, such as water, it becomes possible to aspirate liquid from the container or another liquid reservoir by means of the metering device or to transport it to the metering device by means of a pump and spray it into the suction air flow. Since the metering device is disposed upstream of the centrifugal separator in a flow direction of the suction air flow, the aspirated or transported liquid or water from the container or the liquid reservoir is atomized in the suction air flow and transported into the centrifugal separator. Since the suction air duct runs through the metering device, the suction air flow can be used as a propellant for the metering device by means of which water is aspirated. The atomized water is mixed with the suction air both on the way to the centrifugal separator and in the centrifugal separator, the particles or dust particles in the suction air being wetted with water and thus trapped. The fact that the suction air duct ends in the centrifugal separator also means that the pressure of the suction air flow increases with the result that particles can be effectively wetted with liquid like in a diffusor. By continuously wetting inner walls of the filter, they are moistened at all times and can thus be cleaned continuously. The liquid and the relatively heavy particles can particularly easily be removed from the suction air flow in the centrifugal separator and be collected in the container. An amount of dust conveyed back out of the filter can be significantly reduced and undesired smells can be effectively trapped. When emptying the container, potentially present particulate matter has also been trapped in the liquid and therefore cannot cause health impairment. Thus, an additional cleaning of particulate matter residue is unnecessary. Moreover, it also becomes possible for the filter or the suction device in question to aspirate liquids, which can also be collected in the container.

The metering device and the centrifugal separator can form the suction air duct, and the container can be adjacent to the centrifugal separator. Accordingly, the suction air duct can run solely through the metering device and the centrifugal separator and not through the container. As opposed to liquid filters known from the state of the art, the suction air flow will not be routed through the container with the liquid, which can significantly improve a suction effect. Consequently, the container can be used selectively as a collecting container for particles or dirt for a dry mode of the filter without liquid and for a wet mode of the filter with liquid.

The centrifugal separator can be formed by a cyclone, in particular a single cyclone, which has an immersion tube, in particular a concentric immersion tube. In this case, the suction air flow coming from the metering device can enter the cyclone, wherein the cyclone can also form a diffusor when liquid is added to the suction air flow via the metering device. During a suction process, particles located in the suction air flow can reach a wall of the cyclone and drop down. The suction air thus cleaned leaves the cyclone via the immersion tube. If liquid sprayed into the suction air by the metering device is transported into the cyclone, this liquid additionally sprays particles located on the wall of the cyclone off the wall, whereby the cyclone is continuously cleaned. Optionally, the centrifugal separator can also be composed of a plurality of cyclones, i.e., be a multi-cyclone.

By means of the metering device, liquid can be transported out of the container or a liquid reservoir of the suction device. The liquid reservoir can be another separate container, which can be part of the filter or the suction device. The liquid can be transported by being aspirated by the metering device or a separate pump. In this case, an amount of liquid can be metered irrespective of a suction capacity of the suction device.

The metering device can be formed by at least one jet pump, which can be connected to the container or the liquid reservoir via at least one liquid line. The jet pump can be formed by a Venturi nozzle as an annular nozzle or by a plurality of Venturi nozzles, which can be connected to the container or the liquid reservoir via at least one liquid line. Via the liquid line, liquid or water can be aspirated from the container or the liquid reservoir and supplied to the jet pump permanently. In a particularly simple embodiment, the jet pump can simply be formed by an opening in a channel wall of the suction air duct. The metering device can be coupled to the centrifugal separator and the container as a separate module in such a manner, for example, that the metering device can be easily detached from them and cleaned.

A shut-off valve can be disposed on the liquid line. The shut-off valve can fully close, partially open or fully open the liquid line, meaning an introduction of liquid into the suction air flow via the metering device can be interrupted or adjusted as needed. If the liquid line is closed by the shut-off valve, the filter can be used in dry mode. Even if liquid is located in the container, it is not introduced into the centrifugal separator in this case. Nevertheless, it is possible for liquid to be aspirated by a suction device having the filter and to be separated in the filter. In a particularly simple manner, the shut-off valve can be formed by a flexible tube portion of the liquid line which can be mechanically clamped and thus closed.

A liquid filter can be disposed at a bottom of the container, wherein the liquid filter can be formed by a dam which is formed on the bottom and which can be closed off from an interior of the container by a screen, wherein the liquid line can be connected to the liquid filter and end inside the dam. For example, the dam can be disposed in the center of the bottom, i.e., centrically. In a particularly simple embodiment, the dam can be formed by a circumferential circular web on the bottom. In this case, the screen can be disposed on the dam or be plugged onto the dam and thus separate the interior of the container from an interior of the dam. When the liquid level in the container rises or polluted liquid accumulates in the container, particles can now sink down because of their gravity and be located outside of the dam, allowing liquid loaded with fewer particles to be aspirated via the liquid line by way of the screen. So the metering device can be supplied with essentially cleaned liquid. During an operation of a suction device, the liquid or the water in the container can be progressively saturated with dust particles, the aspirated water being cleaned by the screen and a blockage of the liquid line thus being prevented.

A bottom wall having at least one opening for conveying separated particles from the centrifugal separator into the container can be formed between the centrifugal separator and the container. The bottom wall can separate the centrifugal separator from the container, wherein the bottom wall can be attached to the centrifugal separator or the container. The opening or a plurality of openings formed in the bottom wall can serve to convey particles which have been separated from the suction air flow in the centrifugal separator and sink down. The particles passing through the opening can now drop into the container and be collected therein. A size of the opening is preferably dimensioned in such a manner that the suction air flow conveyed past the opening does not swirl particles in the container again. In one embodiment, the opening can be in the shape of an interrupted ring. In this case, fibers cannot adhere to the opening. In a dry mode of the filter, the liquid can also enter the container through the opening.

The bottom wall can form an essentially plane bottom of the centrifugal separator, wherein an annular web, which can be interrupted in an area of the opening, can be formed on parts of the bottom. A structural height of the centrifugal separator can be substantially reduced by the plane bottom compared to a conical wall usually employed in centrifugal separators. The plane bottom is also significantly easier to clean. The annular web can have a diameter greater than a diameter of an immersion tube of the centrifugal separator. Thus, particles can accumulate between the annular web and the outer wall of the centrifugal separator without being transported to a center of the centrifugal separator and thus below the immersion tube. This increases a functional reliability during longer use of the filter. Still, these particles can be transported along the web toward the opening in the suction air flow owing to the eddy produced in the centrifugal separator. The web can be interrupted in the area of the opening so that particles located below the immersion tube can enter the opening here, as well. A cleaning effect of the filter in dry mode and in wet mode can be significantly improved by the presence of the web.

The opening can be disposed at a radial outer edge of the bottom wall ≤ 90 ° relative to an inlet opening of the suction air flow in the centrifugal separator. Since the particles or liquid accumulate at the radial wall of the centrifugal separator, they can easily enter the opening if the latter is formed at the outer edge of the bottom wall. As has been surprisingly found, a particularly good cleaning effect of the suction air can be achieved if the opening is located at an angle of ≤ 90 °, e.g., an angle of ≥ 70 °, relative to the inlet opening in the bottom wall. The angle is defined as an angle relative to an axis of rotation of the centrifugal separator.

The bottom wall can form an edge at the opening, and at least part of the edge can be formed by a rounded portion, preferably a rounded protrusion extending in the container, with respect to a cross section of the bottom wall. If the particles separated using the filter are fibers, hair or small objects, they can get caught in the opening or at its edge because of the suction air flow swirled in the centrifugal separator and cannot easily pass through the opening into the container. This can be remedied in particular by providing the edge with a rounded portion. The rounded portion can be dimensioned large enough for it to be larger than a cross section of the bottom wall. This can be achieved by forming a protrusion extending into the container on the bottom wall. The protrusion can be a nose or a rounded web. The relatively large rounded portion can effectively prevent fibers or the like from adhering to the edge of the opening.

The bottom wall can be connected to a hinge which allows the container to be opened and closed by pivoting the bottom wall relative to the container. Also, the container and the bottom wall can optionally be connected to a hinge which allows the container to be opened and closed by pivoting the bottom wall or the centrifugal separator relative to the container. This makes it possible for the container to be emptied without having to completely separate it from the centrifugal separator. If a handle is disposed or formed on the container, the hinge can be disposed in such a manner in the area of the handle that the container and the bottom wall can be easily pivoted by operating a lever with one finger, for example. In this case, the container can be opened and closed with one hand, which significantly facilitates a handling of the filter. In principle, it is also possible for the bottom wall or the centrifugal separator to be disposed on a housing of the suction device in a pivotable manner by means of the hinge. A seal, such as a rubber gasket, can be disposed between the container and the bottom wall or the centrifugal separator, the seal effecting a tight closure and thus preventing particles or liquid from escaping. A sealing can in particular result from the establishment of a suction air flow since this causes a vacuum to be formed in the centrifugal separator and the container. A special closure between the container and the bottom wall or the centrifugal separator is no longer necessary in this case.

A handle for handling the container can be disposed on the container. For example, the handle can be molded on the container and be in the shape of an arched handle. The handle makes the container particularly easy to handle and clean. The handle can be designed in such a manner that it can be easily gripped with one hand. Optionally, a liquid line of the metering device can be routed through the handle. In this case, a shut-off valve can be integrated in the handle, in which case the shut-off valve can be easily operated with the hand holding the handle.

A separator plate for separating particulate matter can be disposed above a bottom of the container; the separator plate can divide an interior of the container into an upper receiving space and a lower receiving space, wherein an outer contour of the separator plate can be in contact with an inner wall or an inner side of the container, and a gap can be formed in places between the contour and the inner wall. The separator plate can be essentially plane, making the separator plate easy to clean. Dust, in particular particulate matter, accumulating in the container can enter the lower receiving space through the gap between the inner wall and the contour of the separator plate, whereas larger particles, such as fibers or small objects, can remain in the upper receiving space. In this way, the separator plate prevents the suction air flow, which is established in the centrifugal separator and which can also cause air in the container to move, from raising particulate matter in an undesired manner. Also, emptying the container is made easier since the particulate matter is not inevitably raised during emptying. If a liquid filter is disposed in the container, the separator plate can be combined with the liquid filter. For example, the separator plate can be disposed on or formed together with a screen of the liquid filter. Furthermore, it is advantageous for the bottom of the container to be completely smooth so that the container is easy to clean. Moreover, the container can be circular, which is advantageous in particular if liquid is located in the container. In the case of possible movement of a suction device, liquid in the container may slosh or a wave may form, which may cause the liquid to flow back into the centrifugal separator. If the container is circular, this can be effectively prevented since a wave cannot strike a straight surface head on. , Also, in particular in the wet mode of the filter, smaller particles can advantageously accumulate in the lower receiving space. Hence, the liquid filter can be disposed in the upper receiving space, preventing the smaller particles from being sucked into a liquid line.

The gap can be disposed on a side of the separator plate facing away from or toward a handle. If a handle is formed on the container, it is advantageous for the gap to be formed on the side of the separator plate facing the handle so that particulate matter remains in a lower receiving space and does not enter the upper receiving space through the gap when the container is tilted with one hand from the direction of the handle when emptying the container. Vice-versa, particulate matter can be conveniently disposed of when emptying the container if the gap is disposed on the side facing away. Alternatively, the gap can be disposed at an angle of 90 ° or 270 ° relative to the handle. In this case, the separator plate can be attached to the bottom of the container in such a manner by means of, for example, a plug-in connection that the gap is always oriented as intended by design. In this case, the separator plate can also be easily removed from the container when cleaning the container.

The filter can have a filling level sensor by means of which a filling level of a liquid bath in the container can be detected. It is sufficient for the filling sensor to be able to detect a maximum filling level. This ensures that the container cannot be overfilled with liquid when liquid is aspirated. Once the maximum filling level is reached, shut-off of the suction device can be initiated.

The filling level sensor can be formed by a float in the container and a reed contact outside of the container. For example, the float can be formed by a magnet which actuates the reed contact outside of the container. The reed contact can be disposed adjacent to the float in the suction device. In this case, the filter does not have any electrical lines which can come into contact with liquids. In this manner, a safety of the filter can be significantly improved. Alternatively, it is also conceivable for the filling level sensor to be formed by an optical sensor, a proximity sensor or the like.

An intermediate filter and/or a filter for suspended particles can be disposed in the suction air duct, wherein the intermediate filter and/or the filter for suspended particles can be disposed downstream of the centrifugal separator in the flow direction of the suction air flow. For example, the intermediate filter can be a filter which is made of what is referred to as foam and which is open-cell, thus allowing the suction air flow to pass through. The intermediate filter can be disposed downstream of the centrifugal separator in a flow direction of the suction air flow. The intermediate filter can separate liquid particles or fine dirt particles from the suction air flow and collect them particularly easily. Such an intermediate filter is also easy to clean, for example, by washing. The filter for suspended particles can be disposed downstream of the intermediate filter or the centrifugal separator in the flow direction of the suction air duct. The filter for suspended particles can remove any finer dust particles still present in the suction air from the suction air. The filter for suspended particles can be HEPA filter. The HEPA filter (high-efficiency particulate air filter) can be formed by a fiber mat or a plurality of fiber mat layers.

Inner surfaces of the centrifugal separator and/or the container can be self-cleaning nanostructured surfaces. Each nanostructured surface can be formed by one layer, such as paint. A nanostructured surface can achieve what is referred to as a lotus effect, which essentially prevents particles or liquid from adhering to the surface. This makes the filter significantly simpler to clean.

The suction device according to the invention, in particular the vacuum cleaner, the wet vacuum cleaner or the like, comprises a housing, a suction air duct being formed within the housing, the suction air duct comprising a suction air inlet, in particular for connecting a suction tube to the housing, and a suction air outlet, the suction device comprising a turbine for establishing a suction air flow in the suction air duct and a filter according to the invention. Furthermore, the suction device can comprise a suction tube, a suction nozzle disposed on the suction tube, and a reel disposed within the housing and having a cable for supplying the suction device with power. Other advantageous embodiments of a suction device are apparent from the description of features of the claims dependent on device claim 1.

In the cleaning method according to the invention for cleaning surfaces, in particular in buildings, vehicles or the like, the cleaning method is implemented using a suction device, in particular a vacuum cleaner, a wet vacuum cleaner or the like, comprising a filter, wherein, within a filter housing of the filter, a suction air flow is conveyed through a suction air duct formed in the filter housing, particles being separated from the suction air flow in a centrifugal separator of the filter housing and collected in a container of the filter housing, a metering device of the filter disposed upstream of the centrifugal separator in a flow direction of the suction air flow spraying liquid into the suction air flow. Regarding the advantageous effects of the method, reference is made to the description of advantages of the filter according to the invention. Other advantageous embodiments of the method are apparent from the description of features of the claims dependent on device claim 1.

Hereinafter, a preferred embodiment of the invention will be discussed in more detail with reference to the accompanying drawings.

FIG. 1 is a perspective view of a filter;

FIG. 2 is a longitudinal section view of the filter;

FIG. 3 is a longitudinal section view of a metering device.

A combination of FIGS. 1 to 3 shows a filter 10 for a suction device (not shown), filter 10 being formed by a filter housing 11, within which a suction air duct 12 for conveying a suction air flow (not shown) is formed. Filter housing 11 comprises a centrifugal separator 13 for separating particles from the suction air flow and a container 14 for collecting the separated particles. Filter 10 further has a metering device 15, which is disposed upstream of centrifugal separator 13 in a flow direction of the suction air flow, metering device 15 being configured to aspirate liquid (not shown) located in container 14 from container 14 and to spray it into the suction air flow.

Centrifugal separator 13 is formed by a cyclone 16, which has an immersion tube 17, a circumferential annular outer wall 18, and an essentially plane bottom wall 19. An opening 20 for conveying separated particles into container 14 is formed in bottom wall 19. A prefilter 21 made of foam is disposed upstream of the cyclone 16 or the immersion tube 17, prefilter 21 being followed by an air guide 22. Air guide 22 leads to a turbine (not shown) of the suction device, upstream of which a filter for suspended particles can be disposed.

Metering device 15 is composed of an annular Venturi nozzle 23 and a liquid line 24 connected thereto. When a suction air flow is established by the turbine, liquid located in container 14 is aspirated via liquid line 24 and transported or sprayed into the suction air flow via Venturi nozzle 23. The suction air flow enters cyclone 16 tangentially, which causes swirling, i.e., an eddy to be formed, between immersion tube 17 and wall 18 within cyclone 16. A web 26, which is interrupted in an area of opening 20, is formed at a bottom 25 of bottom wall 19. Opening 20 is disposed on a radial outer edge 27 of bottom wall 19 relative to an inlet opening 28 of the suction air flow in centrifugal separator 13. An edge 29 is formed on opening 20, a rounded protrusion 30, which extends into container 14, being molded on bottom wall 19.

Container 14 is round and has a plane bottom 31, in which liquid line 24 ends. Liquid or water located in container 14 can thus be aspirated by Venturi nozzle 23 via liquid line 24. Liquid line 24 runs via a handle 32, which is molded on container 14. Liquid line 24 is partially formed by a flexible tube 33, which can be blocked by means of a slide 34 on handle 32. Furthermore, a hinge 35 is formed with bottom wall 19 on handle 32, a lever 36 being molded on bottom wall 19. Lever 36 allows bottom wall 19 to be lifted from container 14 in such a manner that container 14 can be emptied or filled.

Furthermore, container 14 has a dam 37 on bottom 31, dam 37 being closed by a screen 38. A separator plate 39, which divides an interior 40 of container 14 into an upper receiving space 41 and a lower receiving space 42, is molded on dam 37. Separator plate 39 is in sealing contact with an inner wall 43 of container 14 and forms a gap 44, which connects upper receiving space 41 to lower receiving space 42.

A float 45 is disposed below bottom wall 19, float 45 being mounted on bottom wall 19 in such a manner that it can pivot from a vertical position into the horizontal position shown here. When a liquid level in container 14 rises, float 45 can actuate a reed contact on the suction device, which initiates a shut-off of the suction device.

When filter 10 is operated in dry mode, a liquid, such as water, is filled in container 14. The suction air flow flowing in is moistened by the water in metering device 15, the water being aspirated from container 14 into Venturi nozzle 23 via liquid line 24, which runs through handle 32. The suction air or the suction air flow flowing in through inlet opening 28 is transported to wall 18, the moistened suction air flow flowing in coming into contact and being mixed with the liquid or the water in a laminar manner. The liquid rinses a surface 46 of wall 18, which reduces an amount of cleaning required later. In cyclone 16, particles (not shown) located in the suction air flow and the liquid are now separated from the suction air flow and reach bottom 25. The dry suction air flow is conveyed out of cyclone 16 into air guide 22 through prefilter 21 via immersion tube 17. Prefilter 21 is disposed in such a manner that a gap 47 is formed between immersion tube 17 and prefilter 21. Gap 47 prevents liquid particles from entering prefilter 21. Furthermore, a collar 48, via which liquid particles can be discharged to the outside, is formed on immersion tube 17.

The liquid charged with particles or dirt now enters container 14 through opening 20. In this process, separator plate 39 separates coarse particles from fine particles. The fine particles accumulate in the liquid below separator plate 39 in lower receiving space 42. Screen 38 retains the coarse particles so that the cleaned liquid can be transported via liquid line 24. For emptying container 14, bottom wall 19 is tilted via hinge 35 with the result that container 14 is open and can be easily emptied. Optionally, a drain opening (not shown), via which the liquid with finer particles can be drained separately, can be provided in bottom 31.

When filter 10 is operated in dry mode, liquid line 24 is squeezed and thus blocked by means of slide 34 by a cam 49 formed thereon. Particles flowing in via the suction air flow are directed at wall 18 and separated from the suction air flow as described above. The particles are conveyed into container 14 at bottom 25 via opening 20. In the process, web 26 prevents particles from reaching a center of bottom 19 and being carried away by suction air flow again. Protrusion 30 in particular deflects fibers or the like so that they cannot become caught on edge 29 of bottom wall 19 or opening 20.

In dry mode, a liquid can also be sucked into filter 10 without metering device 15 being operated. In this case, container 14 can be emptied dust-free, in particular. The filter can be easily cleaned by aspirating clean liquid or water. If liquid is aspirated, a suction function of the suction device is shut off when container 14 is filled and float 45 reaches the horizontal position shown. Once container 14 has been emptied, a suction process can continue. 

1. A filter (10) for a suction device, the filter comprising a filter housing (11) within which a suction air duct (12) for conveying a suction air flow is formed, the filter housing having a centrifugal separator (13) for separating particles from the suction air flow and a container (14) for collecting the separated particles, wherein the filter has a metering device (15) disposed upstream of the centrifugal separator in a flow direction of the suction air flow, the metering device being configured to spray liquid into the suction air flow.
 2. The filter according to claim 1, wherein the metering device (15) and the centrifugal separator (13) form the suction air duct (12), and the container (14) is adjacent to the centrifugal separator.
 3. The filter according to claim 1, wherein the centrifugal separator (13) is formed by a cyclone (16) having an immersion tube (17).
 4. The filter according to claim 1, wherein the metering device (15) is configured to draw liquid from the container (14) or from a liquid reservoir of the suction device.
 5. The filter according to claim 4, wherein the metering device (15) is formed by at least on jet pump (23) which is connected to the container (14) or the liquid reservoir via at least one liquid line (24).
 6. The filter according to claim 5, wherein a shut-off valve (34) is disposed on the liquid line (24).
 7. The filter according to claim 5, wherein a liquid filter is disposed at a bottom (31) of the container (14), the liquid filter being formed by a dam (37) formed on the bottom and closed off from an interior of the container by a screen (38), the liquid line (24) being connected to the liquid filter and ending inside the dam.
 8. The filter according to claim 1, wherein a bottom wall (19) having at least one opening (20) for conveying separated particles from the centrifugal separator (13) into the container is formed between the centrifugal separator (13) and the container (14).
 9. The filter according to claim 8, wherein the bottom wall (19) forms an essentially plane bottom (25) of the centrifugal separator (13), an annular web (26) interrupted in an area of the opening (20) being formed on parts of the bottom.
 10. The filter according to claim 8, wherein the opening (20) is formed on a radial outer edge (27) of the bottom wall (19) ≤ 90° relative to an inlet opening (28) of the suction air flow into the centrifugal separator (13).
 11. The filter according to claim 8, wherein the bottom wall (19) forms an edge (29) at the opening (20), at least part of the edge being formed by a rounded portion, preferably a rounded protrusion (30) extending into the container (14), with respect to a cross section of the wall.
 12. The filter according to claim 8, wherein the bottom wall (19) is connected to a hinge (35) allowing the container to be opened and closed by pivoting the bottom wall relative to the container (14).
 13. The filter according to claim 1, wherein a handle (32) for handling the container is disposed on the container (14).
 14. The filter according to claim 1, wherein a separator plate (39) for separating particulate matter is disposed above a bottom (31) of the container (14), the separator plate dividing an interior (40) of the container into an upper receiving space (41) and a lower receiving space (42), an outer contour of the separator plate being in contact with an inner wall (43) of the container, and a gap (44) being formed in places between the contour and the inner wall.
 15. The filter according to claim 14, wherein the gap (44) is disposed on a side of the separator plate (39) facing toward or away from a handle (32).
 16. The filter according to claim 1, wherein the filter (10) has a filling level sensor configured to detect a filling level of a liquid bath in the container (14).
 17. The filter according to claim 16, wherein the filling level sensor is formed by a float (45) in the container (14) and a reed contact outside of the container.
 18. The filter according to claim 1, wherein an intermediate filter (21) or a filter for suspended particles is disposed in the suction air duct (12), the intermediate filter or the filter for suspended particles being disposed downstream of the centrifugal separator (13) in the flow direction of the suction air flow.
 19. The filter according to claim 1, wherein inner surfaces of the centrifugal separator (13) or of the container (14) are self-cleaning nanostructured surfaces (46).
 20. A suction device, having a housing, a suction air duct (12) being formed in the housing, the suction air duct connecting a suction air inletfor connecting a suction tube to the housing, and a suction air outlet, the suction device comprising a turbine for establishing a suction air flow in the suction air duct and a filter (10) according to claim
 1. 21. A cleaning method for cleaning surfaces, implemented using a suction device, comprising a filter (10), a suction air flow being conveyed through a suction air duct (12) formed in a filter housing (11) of the filter within the filter housing, particles being separated from the suction air flow in a centrifugal separator (13) of the filter housing and collected in a container (14) of the filter housing, wherein a metering device (15) of the filter disposed upstream of the centrifugal separator in a flow direction of the suction air flow sprays liquid into the suction air flow. 